lay down date

lay down daten.— «Booksellers have been required to refrain from selling the book until then, in what is known as a “lay down” date in the publishing world, a tactic typically used for giant best-selling books such as the latest Harry Potter book.» —“Marketing machine for Fiorina book begins” by Therese Poletti Mercury News (San Jose, California) Oct. 5, 2006. (source: Double-Tongued Dictionary)